1. Field of the Invention
The present invention relates to a semiconductor device. Specifically, the present invention relates to a pad pattern of a vertical diffusion metal oxide semiconductor field effect transistor (hereinafter referred to as VDMOS) used in photo-couplers.
2. Description of the Related Art
In a VDMOS, current flows from a drain on a rear surface of a semiconductor chip to an outside surface. A source pad and a gate pad are provided on the main surface. The source pad and gate pad are arranged in the center of the chip so as to be symmetrical, thereby taking into account uniformity of current flow and voltage.
A photo coupler (hereinafter referred to as a bidirectional MOS relay) comprises such a VDMOS, a photoelectromotive element (light receiving element), and an LED.